Preheat oven to 350° F . Line a sheet pan with aluminum foil and coat with canola or vegetable spray.

In a small bowl, cream butter and brown sugar until combined. Add the flour and salt. Carefully mix to combine until it resembles chunky bread crumbs. Transfer into the prepared pan and evenly press the batter into an even layer. Bake for 8 minutes. Cool on a wire baking rack while preparing the coconut topping.

In a large bowl, combine the condensed milk, coconut, and vanilla. Spread over the crust and bake for another 20-25 minutes, until it begins to brown.

Melt the chocolate over a double boiler. Stir until melted and smooth. Pour over cooked coconut bars and spread into an even layer. Allow to cool then refrigerate until hardened, about 1 hour. Cut into 36 squares.